This kind of device which finds its principal use in the closing of doors of cabinets containing apparatus for control of industrial electrical installations, is known for example from the French Pat. No. 1275620, wherein the locking member described can be actuated when the key is introduced into an associated lock.
Such installations are nevertheless subjected to handling by service or maintenance personnel whose respective competence is not equal, and it thus becomes of importance either to be able to prevent certain access, or to limit these occasions of handling to only certain cabinets, or again to permit any person to handle them when these cabinets contain only apparatus or circuits which are not dangerous.
The concern for rationalisation and normalisation of industrial apparatuses formulated by the users moreover leads the manufacturers to provide products having comparable functions and capable of being manufactured starting from elements which are as standardised and are as few in number as possible.